I restore K2F's (in my sleep!) so I'm being honest declaring an interest up front. Having said that, I'm not touting for work, I've got plenty of that! Most K2F's go for about £60 - £100 on ebay. There's no point paying any more because you're going to have to refurbish it anyway which may cost up to £150. You could even buy a refurbished one outright for less than £300. Once restored properly you shouldn't need to touch it. I'm sure a new BTH is a great bit of kit and it doesn't need a battery (just like a K2F!). Fitting any other sort of electronic ignition requires a battery (in most cases 12v) so, instead of worrying about your magneto, you worry about your dynamo! I wouldn't dream of fitting anything other than a restored magneto which should be a cost-effective, stand alone, reliable ignition system. After fitting a good magneto you can sell all that other oversophisticated, fangled, 21st century, heap of wires and electronic wizardry (which has no place on a classic bike), and maybe make a few quid!
